Flexible shaft well drilling equipment



Jan. 26, 1954 J. s. VMmmm: ET Al. FLEXIBLE SHAFT WELL DRILLING EQUIPMENT Filed March 31, 1952 2 Sheets-Sheet 1 INVENTORS. W4/M ATTORNEY.

Jam 26, 1954 J, s, MoCUNEj Elv-VAL n v FLEXIBLE SHAFT WELL DRILLING EQUIPMENT Filed March 51, 1952 2 sheets-sheet 2 if? .J

J/-N (so W/ L/AM E. HAI/VMS,

' INVENTORS. 3%@ rroQA/EY.

Patented Jan. 26, 1954 FLEXIBLE SHAFT WELL DEILLING EQUIPMENT William E. Hanks, Long John S. McCune and Beach, Calif., assign ors to Oilwell Drain Hole Drilling Co., Long Beach, Calif., a corporation of California Application March 31, 1952, Serial N o. 279,556 7 Claims. (Cl. Z55-1.6)

' This invention relates to improvements in well drilling equipment of the type employed for the drilling of so-called drain holes, i. e. lateral bores usually having right-angle deviation from the normal relatively straight or vertical Well bore, and which are drilled to penetrate the formation widely at any of various locations about the main bore to increase the total drainage or inow of production oil from the formation. Particularly contemplated are improvements in such drilling equipment, employing a drill string having a bottom iiexible section or drill collar carrying at its lower end a bit which by reason of the flexible connection of the drill collar may be deiiected at unusually wide or sharp angles from the main bore, and thus enable the drain hole to be drilled at vangles that may approach or go above a horizontal course in relation to the point of deflection or whipstocking.

The invention may be further characterized as dealing with such drain hole equipment employing the combination of a flexible drill collar and a tubular sheath serving various functions, among which are its use as a housing for the full length of the drill collar in the relative positions assumed by the parts before the drain hole drilling commences, also as a carrier for the whipstock, and further as a carrier for such means as may be used to vertically position the whipstoc'a in its bit deecting position within the well. As will appear, under normal operating conditions, the composite ilexible drill collar and its enclosing sheath may be run into the well, oriented in set position for deflection of the drill bit in the proper direction, with the drill collar then being movable downwardly within the sheath to project the bit and progressively the drill collar, out through an opening in the side of the sheath. Thereafter upon completion of an initial drain hole so drilled, the drill collar and bit may be retracted into the sheath and the assembly reset and reoriented for the drilling of one or more additional drain holes in selected directions. After completion of the drilling, the drill collar and sheath assembly may be pulled from the well. Y

Conditions may arise where it becomes desirable to pull the pipe string' and drill collar, leaving the entire sheath or at least the lower extent thereof in the Well. Such desirability may arise, for example, in the event the sheath becomes lodged in the formation, or where it may be found advantageous to retain the sheath in a previously set or oriented position forreception of a rerun bit and drill collar at' some 2 future time, or for passage of a liner into a drilled drain hole.

Accordingly, our major object is to provide for disconnecting of the drill string from the sheath, or from at least the greater lower extent of the sheath, by a type of releasable interconnection between the parts which will assure independent removal of the drill string as a result of simple manipulations. Specifically, the invention contemplates the setting structure including sections interconnected by a left-hand threaded joint, and which may be disconnected at the joint by interengaging shoulders or lugs on both the drill string and sheath, so formed as to assure positive interengagement between the parts, and therefore positive transmission of left-hand rotation of the drill string to the joint to be broken.

All the various features and objects of the invention will be fully understood from the following detailed description of an illustrative embodiment shown by the accompanying drawing, in which:

Fig. l is a general View, for the most part in elevation, showing the drill collar and sheath assembly set in operative position within the Well;

Figs. 2a and 2b are vertically continuing views showing respectively the upper and lower portions of the drill collar and sheath assembly in section;

Fig. 3 is a cross-section on line 3 3 of Fig. 2a;

Figs. 4a and 4b are vertically continuing views illustrating a variational form of the invention; and

Fig. 5 is a section on line 5 5 of Fig. 4a.

The drill string run down within the Wellbore lil is shown to comprise an upper course of standard drill pipe l running to the ground surface, and a iiexible lower section or drill collar l2 connected to the drill pipe by sub I3, the latter having an upper box end receiving at I4 the threaded pin of the tool joint I5, the sub having at its lower end a pin IB threaded into the tapered box of the upper drill collar section I1. At its lower end the drilll collar l2 is connected by way of the knuckle joint generally indicated at i8, with an appropriate drill bit I9.

The-detai1s of a suitable form of flexible drill collar |'2 `are more particularly dealt with in our copending application Ser. No. 279,557, filed on even date herewith.- For present purposes it will suiiice to describe ythe drill collarv as comprising aiseries oftubular sections l1 and 20 interlocked al? ,their` adjacent ends for relative swinging movement by flexible joints 2I each comprising two series of lobes 22 formed on the end of each section and received within corresponding recesses 23 between the similar lobes on the other section, the lobes on each section being spaced at ninety' degrees to present two pairs of ldiametrically opposed lobes, with the pairs at ninety degree angularity, so that the joint sections are relatively movable or swingable in two directionsY at the same location longitudinally of the drill collar. Each section may carry between the lobes suitable anti-friction means to minimize wearing interengagernent with the later Ydescribed sheath, such an anti-friction means comprising typically a rubber ring 24 retained within a recess 25 in the section.

Closed circulation of fluid from the drillstrng thence through the drill collar, knuckle joint I8 to the bit I9, occurs byway of a hose contained within the drill collar bore 2l and suit-` ably held in place as by a hose coupling-type iitting 2K8 securing the upper end of the hose within the bore of section Il, and a tting 29 connecting the lower end of the hose with afloating peripherally sealed insert 33 movable within bore SI.

4The knuckle joint i8 is shown typically to comprise a tubular body 32 containing a curvedseat 33 engageable by the spherical head 34 of the knuckle leg 35 which is capable of swinging movement in the transverse plane dened by the diametrically opposed slots it in the head 3ft Yand which receive the guide pins 3l. In the assembled condition of the knuckle joint, upward displacement of the head is limited'by its engageability with peripherally sealed tubular insert 33, upward movement of which is limited .by the pin shoulder 39. The leg 35 is connected at 6B to the bit shank l I which may carry spiral nights l2 which serve the purpose of guiding and stabilizing the bit during drilling. Y

'The sheath structure generally indicated at 43 comprises an elongated tubular body having upper and lower sections @il and 45 interconnected by a left-hand threaded joint at 'l, the sheath also including suitable means for positioning it vertically in operative location within the well, and for retaining the sheath .in oriented position. Merely as illustrative of` such means, the sheath is shown to carry at its lowerend a leg il having a bottom anchor or shoe 48 which when set down on the bottom o the hole will retain the orientation of the sheath. The lower sheath section contains a side openingri above an inclined solid whipstock face 5l) the purpose of which, as will appear, being to deflect the bit and progressively 4the drill collar, out through the opening is along the drain hole course indicated at 5 I The sub I3 carries a plurality of circularly spaced ribs or lugs 52 which .are positively engageable against shoulders on the upper sheath section di, and formed vfor example as depending lugs 53 on a-tubular insert 5i Vretained within the upper end of the sheath by shearpin 55 which extends at 5t into the Isub I3 and forms a releasable connection between the drill' string and the sheath.

In considering the operation of the equipment, assume the drill collar and sheath assembly Lto be lowered into the Vwell inthe condition shown in Fig. l. Here theshear pin55 connection between, the parts positively but releasably retains the full length of the iiexible drill collar within tioning of the assembly as may be desired for orientation of the whipstock face 50. Following such orientation the imposition of loadY on the drill string shears pin 55 between the sub and insert 54, permitting the bit I9 to be lowered against and deiiected outwardly by the whipstock face 5G. The drain hole 5i vthen is drilled by rotation and progressive advancement of the bit and drill collar out of the sheath into the formation. At completion of the drilling, the

lentire assembly may be removed from the well by raising the drill string from the Fig. Zapositionin which lugs`52 may carry the sheath 'as the tools are pulled from the well.

In the event that following drilling it is desired to pull the drill string and leave the lower :sheath section' in the well, the string may be raised to the Fig. 2a position of interengagement between lugs 52 and 53. Thereupon right-hand rotation of the drill string is positively transmitted through the lugsto the joint ed which by reason ofits left-hand thread formation, may be unscrewed to free the upper sheath section M for withdrawal With the drill. string.

Figs. 4 and 5 illustrate a variational form of the .invention generallyY similar toV the described embodiment but diiiering primarily in that it embodies a form of connection between the drill string and the Sheath whereby ii desired the entire sheath may be leit in the well following a drilling operation. As will appear, this same association between the drill stringr and sheath permits the removed flexible drill collar and bit to again be run into the sheath remaining in the well, .depending upon the requirements of the particular operation being con-ducted.

Referring to Figs. 4a and 4b, the drill pipe il, sub I3, ilexible drill collar I2, knuckle joint i3 and bit I9 correspond to the previously described parts and are given the same reference numerals.

Here the sheathf may comprise upper and lower sections VSI and 52 interconnected at E3 by left-hand threaded or other suitable form cf breakable joint. As before, the upper section may carry ring segments 511i each presenting a depending lug or stop shoulder G5 engageable by a .pair of diametrically opposed lugs 5S on the sub I3. VShear pin 5l releasably interconnects the sheath'and hub. Between the ring segments G4 is a pair of diametrically opposed grooves or ways 68 adapted to receive and pass the subcarried lugs et, as will presently appear. At this point it may be mentioned that the internal diameter'of the sheath within the ring segments til is lsufficiently greater than the external diameter of the drill collar I2y and bit I9 to permit elevation of the drill string up through and out of the sheath.

In considering the operation of the tool, as sume the sheath 6l) to be oriented to proper bit delecting position, and that the drilling is being completed by lowering the drill string (after severance of the shear pin El) and advancement of the bit and drill collar to the desired extent of penetration into the formation. if itis desired to leave the entire sheath and whipstock structure in the hole, the drill string is elevated and turned so that lugs Et are brought 'into alinement with the grooves 68, whereupon the sub, drillcollar'and-bit may be raised out of the sheath. 'Thereafter the bit and drill collar may.

sheath. AIf -it is thereafter desired to Vleave the lower sheath and whipstock section 62 in the well, the lugs 66 may be raised to the Fig. 4a position of engageability with lugs or shoulders 65 and the string then rotated to unscrew the joint at 63 and free the upper sheath section 6I for removal from the well with the drill string.

We claim:

1. The combination comprising a vertically elongated tubular sheath having an opening in its side and including means for deecting a drill bit run down within the sheath outwardly through said opening, the sheath having upper and lower sections interconnected by a joint releasable by counter-clockwise rotation ci the upper section, a drill string including a flexible tubular drill collar carrying a bit and extending downwardly into the sheath through its upper end, said drill collar being movable from an upper position in the sheath downwardly therein to deect and advance the bit outwardly through said opening, and said upper section and the drill string having lugs interengageable in an upper position of the drill collar in the sheath to disconnect said upper section from the lower section by counter-clockwise rotation of the drill string.

2. The combination defined in claim 1, including also releasable means holding the drill collar against downward movement in the sheath from said position in which said lugs on said upper section and drill string are interengageable.

3. The combination denned in claim 1, including also a shear pin releasably interconnecting the drill string and sheath and holding the drill collar against downward movement in the sheath from said upper position in which said lugs on said upper section and drill string are interengageable.

4. The combination as dened in claim 1, in which said lugs of the upper sheath section are formed on a tubular insert within the top of the sheath.

5. The combination comprising a vertically elongated tubular sheath having an opening in its side and including means for deecting a drill bit run down within the sheath outwardly through said opening, the sheath having upper and lower sections interconnected by a joint releasable by counter-clockwise rotation of the upper section, a drill string including an upper standard pipe section and a reticulated iiexible tubular drill collar carrying a bit and extending downwardly Within the sheath, a sub interconnecting the drill pipe and drill collar and extending through the top of the sheath, said drill collar being movable from an upper position in the sheath downwardly Vtherein to deflect and advance the bit through said opening, and said upper section and the sub having lugs interengageable in an upper position of the drill collar in the sheath to disconnect said upper section from the lower section by counter-clockwise rotation of the drill string.

6. The combination dened in claim 5, including also releasable means holding the drill collar against downward movement in the sheath from said position in which said lugs on said upper section and sub are interengageable.

7. The combination deiined in claim 5, including also a tubular insert within said upper section and carrying the sleeve lugs, and a shear pin releasably interconnecting said upper section and the sub in said position in which said lugs on said upper section and sub are interengageable.

JOHN S. MCCUNE. WILLIAM E. HANKS.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 2,196,528 Hughes Apr. 9, 1940 2,544,982 Buttolph Mar. 13, 1951 2,585,207 Zublin Feb. 12, 1952 

